The problem I have with this theory is that the delta between a collection of networks routing by mutual agreement and the internet is:
A. Fuzzy B. Non-Existant C. There is no difference D. Meaningless E. Any and/or All of the above
Pick your favorite answer from the above and you've pretty much got it.
Perhaps it is time for the RIRs to develop clear definitions for the Internet and IP internetworks so that the delta between them is clear.
However, in it's current state of "license for anyone who wants to run a competing RIR for networks that choose to interoperate on this basis" I think it's a pretty bad idea.
The RIR process is the way that the organizations sharing IP number resources reach agreement on who gets what. These organizations have to work together outside of the RIRs to reach agreement on who connects to what and who routes what. If a group of organizations outside the RIR can reach agreement on global internetwork connectivity between them, but separate from the Internet, and if the IP number resource pool is big enough to let these organizations manage their own addressing requirements on that internetwork, then why should the RIRs be upset. Among the many IP networks operated by my company there is a global IPv4 internetwork that is completely separate from the Internet. It has thousands of companies connected to it and, naturally, it uses registered IPv4 addresses. It's not the only such global network. We run one for the financial services industry. There is also such a network for the auto-manufacturing industry, and for the airline industry. And there are probably others as well. --Michael Dillon